Optometer eyepiece

ABSTRACT

A four-component eyepiece for an optometer has an eye relief of about 117mm and is substantially free of chromatic aberration.

BACKGROUND OF THE INVENTION

This invention relates to an eyepiece and more particularly to an optometer eyepiece having four components.

THE DRAWING

FIG. 1 is an optical diagram of an eyepiece viewed transverse to the optical axis.

DESCRIPTION OF THE INVENTION

Referring to FIG. 1, an optometer eyepiece is diagrammatically shown with optically-aligned lenses I, II, III and IV. The first component I is a biconcavo negative singlet, the second component II is a plano-convex positive singlet, the third component III is a biconvex positive singlet and the fourth component IV is a biconvex positive doublet. The eyepiece provides an imaging distance providing an eye relief of about 117mm.

The parameters of the eyepiece according to the present invention are set forth in Table I with axial thicknesses of successive lens components designated T₁ to T₅ and the successive axial spaces from the first component of the eyepiece to the observer's eye are designated S₁ to S₄. The successive lens radii are designated R₁ to R₉ with a minus sign (-) indicating surfaces whose center of curvature lies on the eye side of their vertices. Refractive indices and Abbe numbers of the glasses in the successive lenses are absolute values designated ND₁ to ND₅ and ν₁ to ν₅ respectively.

                                      Table I                                      __________________________________________________________________________                                Index of Abbe                                       Lens                                                                              Radius(R)                                                                              Thickness(T)                                                                           Spacing(S)                                                                             Refraction(ND)                                                                          No.(ν)                                  __________________________________________________________________________        R.sub.1 =+0.90598x                                                          I          T.sub.1 =0.034188x                                                                             1.58<ND.sub.1 <1.60                                                                     ν.sub.1 ≅61                      R.sub.2 =-0.90598x                                                                             S.sub.1 =0.28222x                                              R.sub.3 = > 100x                                                            II         T.sub.2 =0.051282x                                                                             1.58<ND.sub.2 <1.60                                                                     ν.sub.2 ≅61                      R.sub.4 = 1.6036x                                                                              S.sub.2 =0.0008547x                                            R.sub.5 =-1.5231x                                                           III        T.sub.3 =0.068376x                                                                             1.58<ND.sub.3 <1.60                                                                     ν.sub.3 ≅61                      R.sub.6 = 0.89786x                                                                             S.sub.3 =0.17239x                                              R.sub.7 =-1.8352x                                                                      T.sub.4 =0.08547x                                                                              1.58<ND.sub.4 <1.60                                                                     ν.sub.4 ≅61                   IV R.sub.8 = 0.42966x                                                                     T.sub.5 =0.059829x                                                                             1.77<ND.sub.5 <1.79                                                                     ν.sub.5 ≅26                      R.sub.9 = 1.1479x                                                                              S.sub.4 =0.9982x                                            wherein x is 115 to 119mm.                                                     __________________________________________________________________________

A specific embodiment of the present invention wherein x is equal to 117mm and has the following values with radii, spacings and thicknesses being in millimeters.

                                      Table II                                     __________________________________________________________________________                                Index of Abbe                                       Lens                                                                              Radius(R)                                                                              Thickness(T)                                                                           Spacing(S)                                                                             Refraction(ND)                                                                          No.(ν)                                  __________________________________________________________________________        R.sub.1 = 106.00                                                            I          T.sub.1 = 4.0   ND.sub.1 =1.589                                                                         ν.sub.1 =61.12                             R.sub.2 =-106.00                                                                               S.sub.1 =33.02                                                 R.sub.3 = ∞                                                           II         T.sub.2 = 6.0   ND.sub.2 =1.589                                                                         ν.sub.2 =61.12                             R.sub.4 = 187.62                                                                               S.sub.2 = 0.10                                                 R.sub.5 =-178.20                                                            III        T.sub.3 = 8.0   ND.sub.3 =1.589                                                                         ν.sub.3 =61.12                             R.sub.6 = 105.05                                                                               S.sub.3 =20.17                                                 R.sub.7 =-214.715                                                                      T.sub.4 =10.0   ND.sub.4 =1.589                                                                         ν.sub.4 =61.12                          IV R.sub.8 =  50.27                                                                       T.sub.5 = 7.0   ND.sub.5 =1.784                                                                         ν.sub.5 =25.76                             R.sub.9 =134.30                                                                                S.sub.4 =116.79                                             __________________________________________________________________________ 

What is claimed is:
 1. A four component optometer eyepiece being substantially free of chromatic aberration comprising a biconcave negative singlet I, a plano-convex positive singlet II, a biconvex positive singlet III and a biconvex positive doublet IV all aligned in sequence along an optical axis and having the values set forth below with axial thicknesses of the successive lens components being designated T₁ to T₅, successive axial spaces from the first component to an observer's eye being designated S₁ to S₄, successive lens radii being designated R₁ to R₉ where the minus sign (-) indicates surfaces whose center of curvature lies on an observer's side of their vertices, refractive indices and Abbe numbers are absolute values designated ND₁ to ND₅ and ν₁ to ν₅, respectively,

    ______________________________________                                                        Thick-           Index of                                                      ness             Refraction                                                                              Abbe                                  Lens Radius(R) (T)      Spacing(S)                                                                             (ND)     No. ( )                               ______________________________________                                              R.sub.1 =                                                                      0.90598x                                                                                 T.sub.1 =        1.58<                                          I    R.sub.2 = 0.034188x        ND.sub.1 <1.60                                                                          ν.sub.1 =61                             0.90598x           S.sub.1 =                                                   R.sub.3 =          0.28222x                                                     100x                                                                                    T.sub.2 =        1.58<                                          II   R.sub.4 = 0.051282x        ND.sub.2 <1.60                                                                          ν.sub.2 =61                             1.6036x            S.sub.2 =                                                   R.sub.5 =          0.0008547x                                                  1.5231x                                                                                  T.sub.3 =        1.58<                                          III  R.sub.6 = 0.068376x        ND.sub.3 <1.60                                                                          ν.sub.3 =61                             0.89786x           S.sub.3 =                                                   R.sub.7 =          0.17239x                                                    -1.8352x                                                                                 T.sub.4 =        1.58<                                               R.sub.8 = 0.08547x         ND.sub.4 <1.60                                                                          ν.sub.4 =61                        IV   0.42966x                                                                                 T.sub.5 =        1.77<                                               R.sub.9 = 0.059829x        ND.sub.5 <1.79                                                                          ν.sub.5 =26                             1.1479x            S.sub.4 =                                                                      0.9982x                                                and x is 115 to 119mm.                                                         ______________________________________                                    


2. The eyepiece according to claim 1 wherein x is 117mm, ND₁ to ND₄ are 1.589, ND₅ is 1.784, ν₁ to ν₄ are 61.12 and ν₅ is 25.76. 